Marriage and Obesity

Written By: Jason Shafrin
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Nov•
28•07

Are married people more likely to be obese than single individuals? More to the point, does being married cause obesity? Married individuals are generally older than never-married individuals and since age is correlated with obesity, there could be a spurious relationship between marriage and obesity.

One may think that married individuals are not on the “single’s market” and thus may not have a strong incentive to maintain an athletic physical appearance to attract mates. As stated in Sobal (1984), “We may hypothesize that as a marital relationship becomes solidified the partners may feel less need to maintain external appearances important in attracting a mate.” On the other hand, a paper by Rand, Kuldau and Robbins (JAMA 1982) found that individuals who had jejunoileal bypass surgery to decrease obesity had improved marriage relationships. Thus, those who value their marriage may wish to avoid being overweight to make the marriage experience more pleasurable.

If healthier individuals can more easily attract a mate, than it would be the case that married individuals will be less overweight than single individuals. Averett and Korenman (Int J Obesity 1999) found that obesity is associated with a lower probability of marriage. Gortmaker et al. (NEJM 1993) use the NLSY to conclude that individuals who where overweight in their adolescent years are 20% less likely to be married seven years later than a healthy-weighted individual. Cawley, Joyner and Sobal (Rationality and Society 2006) confirm that for adolescents “dating is less likely among heavier girls and boys and among shorter girls and boys.”

Sobal, Rauschenbach and Frongillo (Soc Sci Med 1992) categorizes the relationship between obesity as marriage through two distinct mechanisms: “marital selection” and “marital causation.” Non-overweight people are more likely to attract a mate, and thus “select” into marriage. However, if marriage “causes” weight gain–due to a more sedentary lifestyle, lower mate attraction incentive, childbirth, etc.–than a researcher may find that married individuals are more overweight on average.

The best way to control for these two conflicting effects is to use a panel data set. Cawley (JHR 2004) employs the 1979 NLSY, using lagged BMI as an instrument for current BMI and individual fixed effects to control for time-invariant individual characteristics. Other studies have used sibling weight (Avarett and Kroenman (JHR 1996), or spousal weight as an instrument for current BMI. Using data from the National Survey of Personal Health practices and consequences, the Sobal, Rauschenbach and Frongillo paper finds that “it appears that there is a relationship between fatness and marital status for men, with married men fatter and more obese.”

Nevertheless, more research is needed to refine the exact manner in which marriage affects obesity.